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Section I - Multiple Choice (2 Viewers)

Jassinta

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fucked up question 8 or 9 dont remember, it was the curve and which point is greater than 0 and equal to 0 , stupidest thing -.-
The answer to that one was point B on the graph, basically it asked you which one was the point of inflection. Which I didn't know until I went and asked my Maths teacher after the exam. And I got it wrong. But anyway.
 

Queenroot

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The answer to that one was point B on the graph, basically it asked you which one was the point of inflection. Which I didn't know until I went and asked my Maths teacher after the exam. And I got it wrong. But anyway.
C is a point of inflextion as well as B. So goddamn confusing.
 

Firmin

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im pretty sure 10 was b

remember velocity = speed WITH direction

and -acceleration means negative/going down
so i think it's B
10 is definitely D. By Newton's second law F=ma acceleration is interchangeable with force. If you act a force in a direction that is opposite to the currently velocity of a particle it will slow down. ie. If your chair is rolling forwards and someone pushes (accelerates) you in the opposite direction you will slow down.
 

bedpotato

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10 is definitely D. By Newton's second law F=ma acceleration is interchangeable with force. If you act a force in a direction that is opposite to the currently velocity of a particle it will slow down. ie. If your chair is rolling forwards and someone pushes (accelerates) you in the opposite direction you will slow down.
Is this in the 2U course?...
 

hjed

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10 is definitely D. By Newton's second law F=ma acceleration is interchangeable with force. If you act a force in a direction that is opposite to the currently velocity of a particle it will slow down. ie. If your chair is rolling forwards and someone pushes (accelerates) you in the opposite direction you will slow down.
You'd be correct ... if speed was a vector, speed is not a vector. The current speed of the particle is negative, if it has positive acceleration than speed is increasing. Velocity on the other hand would be decreasing.
(Nb. force, acceleration and velocity are vectors, speed is not. Vectors are defiantly in the syllabus. )
 

Firmin

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You'd be correct ... if speed was a vector, speed is not a vector. The current speed of the particle is negative, if it has positive acceleration than speed is increasing. Velocity on the other hand would be decreasing.
(Nb. force, acceleration and velocity are vectors, speed is not. Vectors are defiantly in the syllabus. )
http://www.physicsclassroom.com/class/1dkin/u1l1d.cfm

Instantaneous velocity can be used interchangeably with speed (In linear cases).
 
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bedpotato

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No, but it's just a another way to put it because a lot of people don't understand that negative acceleration =/= deceleration
Okay, but the question didn't say that force was being applied on the particle?

I'm looking it a different way.

If a > 0, the particle is travelling at an increasing speed.
If v < 0, the particle is travelling towards the left (or towards the origin).

For questions like: for what values of x is f(x) is increasing, isn't it when f'(x) > 0 ?

look at v as f(x) and a as f'(x)

Since a [ f'(x) ] is > 0, v [ f(x) ] is increasing. So the speed is increasing.

Therefore, the particle is moving towards the origin at an increasing rate (or speed, whatever it was).
And v < 0, so the particle is moving toward the origin.

Screw this.
Another mark lost.
Another band down the drain.
 

Menomaths

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Okay, but the question didn't say that force was being applied on the particle?

I'm looking it a different way.



And v < 0, so the particle is moving toward the origin.

Screw this.
Another mark lost.
Another band down the drain.
What's the answer?
 

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